Bone anchor

ABSTRACT

An anchor assembly can be couplable to a bone and can include an anchor and a housing. The anchor can include a shank securable to bone and a head coupled to a proximal portion of the shank. The housing can include a proximal portion including an anchor bore and a distal portion including a secondary bore configured to engage the anchor to limit angulation of the anchor relative to the housing.

CLAIM OF PRIORITY

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/724,811, filed on Aug. 30, 2018, the benefit ofpriority of which is claimed hereby, and which is incorporated byreference herein in its entirety.

BACKGROUND

This document pertains generally, but not by way of limitation, tosystems and methods for fixation of bones during orthopedic procedures.More particularly, this disclosure relates to, but not by way oflimitation, vertebral bone anchors. Orthopedic devices such as rods,plates, tethers, staples, and other devices can be used in variousspinal procedures to correct abnormalities (e.g., scoliosis) or toaddress injuries (e.g., vertebral fracture). In some spinal procedures,anchors and rods can be secured along a vertebral column to vertebrae tostabilize a region of the spine. In these procedures, pedicle screws (orvertebral anchors) can be secured to individual vertebra and tiedtogether with a connecting rod.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 illustrates an exploded view of an anchor assembly from ananterior perspective, in accordance with at least one example of thisdisclosure.

FIG. 2 illustrates a cross-sectional view of an anchor assembly acrosssection 2-2 of FIG. 1, in accordance with at least one example of thisdisclosure.

FIG. 3A illustrates an isometric view of an anchor assembly, inaccordance with at least one example of this disclosure.

FIG. 3B illustrates an isometric view of an anchor assembly, inaccordance with at least one example of this disclosure.

FIG. 3C illustrates an isometric view of an anchor assembly, inaccordance with at least one example of this disclosure.

FIG. 4 illustrates a lateral view of a vertebral column and fixationassembly, in accordance with at least one example of this disclosure.

FIG. 5A illustrates an isometric view of an anchor housing, inaccordance with at least one example of this disclosure.

FIG. 5B illustrates an isometric view of an anchor housing, inaccordance with at least one example of this disclosure.

FIG. 5C illustrates a bottom view of an anchor housing, in accordancewith at least one example of this disclosure.

FIG. 6 illustrates a bottom view of an anchor housing, in accordancewith at least one example of this disclosure.

FIG. 7 illustrates a bottom view of an anchor housing, in accordancewith at least one example of this disclosure.

FIG. 8 illustrates a bottom view of an anchor housing, in accordancewith at least one example of this disclosure.

FIG. 9 illustrates a bottom view of an anchor housing, in accordancewith at least one example of this disclosure.

DETAILED DESCRIPTION

Bone anchors can be used together with connecting members (such as rigidand semi-rigid rods) to straighten a region of a human spine to addressan abnormality (e.g., scoliosis), to stabilize a spine following aninjury (e.g., fractured vertebrae), or to address degeneration of thespine caused by disease. In one example procedure, anchors are driveninto vertebrae and are manipulated from outside of the cavities. Thehousing of the anchor can be positioned with respect to the shank of theanchor and the housings can be individually and collectively positionedalong the spinal column to receive a connecting rod. The connecting rodcan extend through two or more housings and can be secured to eachhousing by a closure top or set screw.

In some procedures, disruption of muscle around the vertebral column maybe reduced by using a technique that secures vertebral anchors along acortical trajectory. That is, the trajectory along which the shank ofthe anchor extends into the vertebra to which it is secured can bethrough primarily cortical bone as opposed to a standard trajectorywhere the shank can extend into the vertebral body. In addition tohelping to limit muscle disruption, this technique may enable use ofsmaller diameter and length anchors while maintaining good fixation.However, to allow for proper support of the connecting member to thehousing, the cortical trajectory can require relatively largerangulation of the shank relative to the housing of the anchor in themedial to lateral and/or caudal to cranial directions. Further, becausethese procedures are performed with relative little work space (within aretracted opening), it is desirable to achieve relatively largeangulation at multiple positions of the shank relative to the housingwhile still retaining the shank within the housing.

This disclosure addresses these problems by including rounded notches ina distal end of the housing. More specifically, to provide theangulation required for use of a cortical trajectory, this disclosureproposes to use a secondary bore in the anchor housing that includes, inone example, rounded notches or corners configured to allow for arelatively high degree of angulation of the anchor relative to thehousing to allow the cortical trajectory to be used while still allowingthe housings to be aligned to accept a connecting rod.

Also, in some examples, the anchor housing can include multiple roundednotches in a symmetrical arrangement (such as a square shape withrounded corners from a distal perspective). This can allow the housingto be positioned at the required angulation relative to the anchor whenthe housing in multiple positions, helping to reduce a requirement oforienting the housing relative to the anchor, which can save time andenergy during a procedure.

This discussion is intended to provide an overview of subject matter ofthe present patent application. It is not intended to provide anexclusive or exhaustive explanation of the invention. The discussionbelow is included to provide further information about the presentpatent application.

FIG. 1 illustrates an exploded view of an anchor assembly 100 from ananterior perspective, in accordance with at least one example of thisdisclosure. The anchor assembly 100 can include a housing and an anchorinsertable through the housing and into bone for securing the anchorassembly 100 to a bone, in some examples.

The anchor assembly 100 can include an anchor 102, a housing 104, alower piston 106, a biasing element 108, and an upper piston 110. Theanchor 102 can include a head 112 and a shank 114. The housing 104 caninclude a proximal portion 115, an anchor bore 116, and a distal portion117. Also shown in FIG. 1 are axis A and orientation indicators Proximaland Distal.

The anchor 102 can be a fastener configured to secure to a work piece,such as a bone, plate, prosthesis, or other device used in a surgery oroperation. In other examples, the anchor 102 can be configured to engagewood, plastics, metals, and the like, for applications outside ofsurgical procedures. Anchor 102 can be comprised of plastics, metals,composites, combinations thereof, and the like. In some examples, theanchor 102 can be comprised of biocompatible materials such as such asstainless steels, cobalt-chromium, titanium variations, polyether etherketone (PEEK), and combinations thereof.

The anchor 102 can include a head 112 located at a proximal portion ofthe anchor 102, which can connect to the shank 114. The head 112 canhave a diameter larger than that of the shank 114 in some examples suchthat the shank 114 can extend through the housing 104 and so that thehead 112 is limited from passing through a distal opening of the housing104. The shank 114 can extend distally away from the head 112 and caninclude a threaded portion, in some examples, for engaging bone.

The housing 104 can include the proximal portion 115 connected thedistal portion 117 with the anchor bore 116 extending through a proximalend of the proximal portion 115 along axis A and terminating within thedistal portion 117. The anchor assembly 100 can be a top-loadingassembly. The housing 104 can include a secondary opening to allow theshank 112 to extend through the housing but not the head 112. Thehousing 104 can thereby be configured to the head 112 in the housing104.

The lower piston 106 can be a supporting member configured to engage thehead 112 and to be supported thereby. The biasing element 108 can be aresilient element such as a spring. In some examples, the biasingelement 108 can be a wave spring. In other examples, the biasing element108 can be other springs or resilient members, such as a compressionspring or compressible and resilient members comprised of materials suchas rubbers, plastic, and the like. The upper piston 110 can be asupporting member configured to engage a proximal portion of the biasingelement and configured to support a connecting member (shown in FIG. 2).

In assembly of some examples, the shank 114 of the anchor 102 can beinserted proximally-to-distally through the anchor bore 116 of thehousing 104 such that the shank 114 extends distally out of the housing104. The shank 114 can then be secured to a bone of a patient, asdiscussed below in further detail. A position of the housing 104relative to the anchor 102 can be set during securing of the shank 114into the bone. The position can be fixed by a force applied on thehousing 104 by the head 112 when the shank 114 is secured to the bone.

Once the shank 114 is secured to the bone, the lower piston 106, thebiasing element 108, and the upper piston 110 can be inserted into theanchor bore 116 such that the lower piston 106 engages the head 112. Thebiasing element 108 can be disposed between the lower piston 106 and theupper piston 110 to bias the upper piston 110 away from the lowerpiston. The upper piston 110 can receive the connecting member therein,which can be secured within the housing 104 by a closure top or setscrew.

As discussed in further detail below, the secondary bore (or opening) inthe distal portion 117 of the housing 104 can be configured to allow theanchor 102 to be oriented at various angles with respect to axis A andtherefore relative to the housing 104. More accurately, when the anchor102 is secured to bone, the housing 104 can be oriented at variouspositions relative to the anchor 102 and to the bone. In some examples,the housing 104 can allow for the anchor 102 to be positioned atrelatively extreme angles (such as 30 degrees, 35 degrees, 40 degrees,and the like) with respect to axis A to allow for the anchor 102 to besecured to a vertebra using a cortical bone technique. Though thisdisclosure references use of anchor assembly 100 using a corticaltrajectory technique, the anchor assembly 100 can be used in variousother vertebral anchoring techniques where the benefits of the anchorassembly 100 (such as the anchor 102 can be oriented at various angleswith respect to the housing 104) can be useful.

FIG. 2 illustrates a cross-sectional view of the anchor assembly 100across section 2-2 of FIG. 1, in accordance with at least one example ofthis disclosure. The anchor assembly 100 can include the anchor 102, thehousing 104, the lower piston 106, the biasing element 108, the upperpiston 110, and the connecting rod 118. The anchor 102 can include thehead 112, the shank 114, a tool interface 120, and a neck 121. Thehousing 104 can include the proximal portion 115, the anchor bore 116,the distal portion 117, a secondary bore 122, the anchor threading(helical groove) 124, a head bore 126, a retaining portion 127, a pistonbore 128, and closure top threading 130. The lower piston 106 caninclude a washer notch 133. The upper piston 110 can include a washernotch 134. Also shown in FIG. 2 are axis A, diameter D1, diameter D2,diameter D3, and orientation indicators Proximal and Distal.

Anchor assembly 100 of FIG. 2 can be consistent with anchor assembly 100of FIG. 1, except that FIG. 2 shows additional details of anchorassembly 100. For example, FIG. 2 shows the tool interface 120 of head112 which can be configured to interface with a tool and/or a tool bitto receive a torque from a tool to rotate the anchor 104 into and/or outof a bore (such as a bore in a vertebra).

FIG. 2 also shows that anchor 102 can include the neck 121, which can bea necked-down (or reduced diameter) portion of the anchor 104 connectingthe head 112 to the shank 114. In some examples the neck 121 can havethe diameter of D1, the head 112 can have the diameter D2, and the shankcan have the diameter D3. The neck 121 can be positioned along theanchor 102 such that the neck 121 is the portion of the anchor 121 thatcontacts the distal portion 117 of the housing 104 to limit rotation orangulation of the anchor 102 with respect to (or relative to) thehousing 104. Because the diameter D1 of the neck 121 is smaller thandiameters D2 and D3, contact between the neck 121 and the distal portion117 of the housing will occur at a greater angle of the anchor 102 withrespect to axis A and the housing 104.

The housing 104 can also include the secondary bore 122, which can be anundercut, opening, or series of bevels at a distal end of the distalportion 117 of the housing 104. In some examples, the secondary bore 122can be configured to contact the neck 121 to limit the angulation orrelative angle of the anchor 102 with respect to the housing 104.

The housing 104 can also include the anchor threading (or helicalgroove) 124, which can be threading in the housing 104. The helicalgroove can be positioned in the housing 104 where the housing 104 tapersradially inward to create the retaining portion 127 (at the distalportion 117). The radially inward taper of the retaining portion 127 canbe configured to retain the head 112 of the anchor 102 in the housing104. Because the threading of the shank 114 can be as wide or wider thanthe head 112 of the anchor, anchor threading 124 can be required toallow the shank 114 to pass through the retaining portion 127 of thehousing 104.

The head bore 126 of the housing 104 can be sized to allow the head 112to pass through to the retaining portion 127 of the housing 104 wherethe head 112 can be retained. The head bore 126 can also be sized toretain the bottom piston 106 therein. The piston bore 128 can be sizedto receive the top piston 110 in the housing, where the top pistonincludes a flared portion having a diameter larger than that of thebottom piston 106. The top piston 110 can be configured to support theconnecting member 118 within the housing 104. The closure top threading130 can be threading in housing 104 configured to threadably receive aclosure top to secure the connecting member 118 within the anchor bore116 of the housing 104.

The washer notch 133 of the lower piston 106 can be a notch or undercutin the lower piston 106 sized and shaped to partially retain the biasingelement 108. Similarly, the washer notch 134 of the upper piston 110 canbe a notch or undercut in the upper piston 110 sized and shaped topartially retain the biasing element 108. Together, the washer notches133 and 134 and the housing bore 126 can contact the biasing element toretain the biasing element 108 between the lower piston 106 and theupper piston 110 to bias the upper piston 110 away from the lowerpiston.

FIG. 3A illustrates an isometric view of the anchor assembly 100 from ananterior perspective, in accordance with at least one example of thisdisclosure. FIG. 3B illustrates an isometric view of the anchor assembly100 from a lateral perspective, in accordance with at least one exampleof this disclosure. FIG. 3C illustrates an isometric view of an anchorassembly from a distal perspective, in accordance with at least oneexample of this disclosure. FIGS. 3A, 3B, and 3C are discussed belowconcurrently.

The anchor assembly 100 can include the anchor 102, and the housing 104.The anchor 102 can include the head 112, the shank 114, and the neck121. The housing 104 can include the proximal portion 115, the anchorbore 116, the distal portion 117, and the secondary bore 122. Thesecondary bore 122 can include corner notches 130 a-130 d (a firstangled notch 130 a, a second angled notch 130 b, a third angled notch130 c, and a fourth angled notch 130 d; collectively referenced ascorner notches 130) and straight portions 132 a-132 d (visible in FIG.3C only and). Also shown in FIGS. 3A-3C are axis A1, axis A2, axis A3,angle Θ, and orientation indicators Proximal, Distal, Medial, Lateral,Anterior, and Posterior.

Anchor assembly 100 of FIGS. 3A-3C can be consistent with anchorassembly 100 of FIGS. 1 and 2, except that FIGS. 3A-3C show additionaldetails of anchor assembly 100. For example, FIG. 3B shows how the neck121 can contact the corner notch 130 d of the secondary opening 122 toobtain the angle Θ of angulation of the anchor 102 with respect to thehousing 104.

More specifically, the secondary opening 122 can include multiple edges,such as bevels, chamfers, J grooves, scotias, or the like. In someexamples, the secondary opening can include corner notches 130 a-130 dwhich can each be rounded corner bevels, where each of the plurality ofbevels curves along a face of each of the corner notches 130 a-130 d.

In some examples, each of the corner notches 130 can be connected bystraight portions 132 a-132 d. In some examples, each of straightportions 132 a-132 d can be bevels in the secondary opening 122, eachhaving a substantially flat or planar face. The first straight portion132 a can be connected to the first angled notch 130 a and the secondangled notch 130 b; the second straight portion 132 b can be connectedto the second angled notch 130 b and the third angled notch 130 c; thethird straight portion 132 c can be connected to the third angled notch130 c and the fourth angled notch 130 d; and, the fourth straightportion 132 d can be connected to the first angled notch 130 a and thefourth angled notch 130 d.

This example of the secondary opening 122 can have a geometric shapesubstantially of a square with rounded corners from a distal perspective(as shown in FIG. 3C). As shown in FIGS. 3A-3C contact between the neck121 and angled notch 130 d can create an angulation of the shank 114with respect to the housing 104 at the angle Θ, where the angle Θ is theangle between axis A1 (of the housing 104 and housing anchor bore 116)and axis A2 (extending along anchor 102). In some examples, the angle Θcan be 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 degrees, or the like(including degrees between values listed). The ability to provide theangle Θ at high angulation can allow for the anchor assembly 100 to beused in a procedure where the anchor 102 is installed using a corticaltrajectory. Also, the anchor assembly 100 can be useful in various othervertebral anchor installation techniques where high angulation isdesired or required.

Also, by providing four of curved notches 130 a-130 d, each capable ofproviding angulation at the angle Θ of the shank 114 relative to thehousing 104 while still retaining the shank 114 within the housing 104,the anchor assembly 100 provides an anchor housing 104 that issymmetrical about two planes and therefore can be quickly positioned toa desired orientation during a procedure, helping to save the physiciantime and energy during what can be a relatively time-intensiveprocedure.

In the arrangement of this example, contact between the neck 121 and thestraight portions (any of 132 a-132 d) can result in angulation of theanchor 102 with respect to the housing 104 at an angle that is lowerthan the angle Θ. In this example each of the angled notches 130 a-130 dcan produce an angle Θ that is the same. In other examples, each of theangled notches 130 a-130 d can produce an angle Θ that is different.

FIG. 4 illustrates a lateral perspective of a vertebral column 10 and afixation assembly 400, in accordance with at least one example of thisdisclosure. In FIG. 4, the fixation assembly 400 can be secured to thevertebral column 10, as discussed in further detail below. Any of thepreviously discussed anchor assemblies can be secured to such avertebral column.

Vertebral column 10 can include a vertebra 12, which can include avertebral body 14, a disk 16, a spinous process 18, and a transverseprocess 20. The fixation assembly 400 can include housings 402 a-402 b,a connecting member 404, and anchors 406 a-406 d, where each of thehousings 402 a-402 b corresponds to one of the anchors 406 a-406 d. Alsoshown in FIG. 4 are axis A1, axis A2, angle Θ, and orientationindicators Superior, Inferior, Anterior, and Posterior.

The fixation assembly 400 of FIG. 4 can operate consistently with theassemblies described in FIGS. 1-3C above, except that FIG. 4 shows theassembly 400 installed in vertebral column 10. As shown in FIG. 4, eachof the anchors 406 a-406 d are secured to cortical bone of individualvertebra of the vertebral column 10.

When each of the anchors 406 a-406 d are installed within respectivevertebrae using the cortical trajectory, the anchors 406 a-406 d mayhave a high degree of angulation with respect to their respectivehousings 402 a-402 d. For example, axis A1 can extend substantiallythrough an anchor bore of housing 402 b and axis A2 can extendsubstantially along a shank of the anchor 406 b. The angle Θ can beformed by axes A1 and A2. In the example shown in FIG. 4, the angle Θcan represent a large angulation of the anchor 406 b relative to thehousing 402 b in a inferior-to-superior direction, such as 35 degrees(or other angulations as described above). In some examples, anchor 406b can be positioned to create a large angulation relative to the housing402 b in a medial-to-lateral direction, such as 35 degrees (or otherangulations as described above).

Because each of the housings 402 a-402 d can include rounded notchesconfigured to allow for the relatively large angulations of the anchors406 a-406 d relative to the housings 402 a-402 d, respectively, thehousings 402 a-402 d can be aligned to allow the connecting member 404to be relatively easily installed following installation of the anchors,which can save time and energy during a procedure.

FIG. 4 also shows that the anchors 406 a-406 d can be installed usingdifferent angulations. For example, the angulation of anchors 406 d canbe smaller than that of the anchor 406 a. In this way, the housings 402a-402 d can be used to create a variety of angulations of the anchors406 a-406 d so that a single housing design can be used for multiplevertebral installations.

FIG. 5A illustrates an isometric view of an anchor housing 500, inaccordance with at least one example of this disclosure. FIG. 5Billustrates an isometric view of the anchor housing 500, in accordancewith at least one example of this disclosure. FIG. 5C illustrates abottom view of an anchor housing 500, in accordance with at least oneexample of this disclosure. The anchor housing 500 can be similar tothose of anchor assemblies 100 and 400 above; however, FIGS. 5A-5C showadditional details of the housing 500. FIGS. 5A-5C are discussed belowconcurrently.

The housing 500 can include a proximal portion 515, an anchor bore 516,a distal portion 517, a secondary bore 522, and helical grooves 524. Thesecondary bore 522 can include corner notches 530 a-530 d (first anglednotch 530 a, second angled notch 530 b, third angled notch 530 c, andfourth angled notch 530 d), straight portions 532 a-532 d, and edges 536a-536 g. Also shown in FIGS. 5A-5C are axis A, and orientationindicators Proximal, Distal, Medial, Lateral, Anterior, and Posterior.

In some examples, each of the corner notches 530 a-530 d can beconnected by straight portions 532 a-532 d. In some examples, each ofstraight portions 532 a-532 d can be bevels of the secondary opening522, each having a substantially flat or planar face. The first straightportion 532 a can be connected to the first angled notch 530 a and thesecond angled notch 530 b, the second straight portion 532 b can beconnected to the second angled notch 530 b and the third angled notch530 c, the third straight portion 532 c can be connected to the thirdangled notch 530 c and the fourth angled notch 530 d, and the fourthstraight portion 532 d can be connected to the first angled notch 530 aand the fourth corner notch 530 d.

Each of the edges 536 a-536 g can each be located where each of thecorner notches 530 a-530 d meets one of the straight portions 532 a-532d. For example, the edge 536 a can be a connection between the cornernotch 530 a and the straight portion 530 a; and, the edge 536 b can bethe connection between the straight portion 532 a and the corner notch530 b. In some examples, each of the straight portions 532 a-532 d canbe positioned relative to the corner notches 530 a-530 d such that eachof the edges 536 a-536 g can be configured to limit or minimizeengagement of the edges 536 a-536 g with an anchor. That is, thestraight portions 532 a-532 d can be positioned to limit radially inwardextension of each of the edges 536 a-536 g from the secondary bore 522.This can help to promote smooth movement of the anchor between thecorner notches 530 a-530 d. This can also help prevent relative movementof the anchor to the housing 500, because the contact between the anchorand the secondary bore 522 can be relatively consistent.

FIGS. 5A-5C also show that the helical grooves 524 can terminate nearwhere straight portion 532 a meets corner notch 530 b and where straightportion 532 d meets corner notch 530 d (diagonally across for eachother). Terminating the helical grooves 524 at these positions can helpto limit interference of the helical grooves 524 with the secondaryopening 522, which can help to simplify manufacturing and can help allowfor desired angulation of the anchors with respect to the housing 500.However, the helical grooves 524 can also be placed relative to thesecondary opening 5522 such that the head of the anchor can contact thehelical grooves 524 to provide a sharp edge for contact with the headwhen the anchor is fully screwed into the bore and when the head appliesa force on the housing 500. This can help prevented relative movement ofthe head to the housing 500 following installation of the anchorassembly.

FIG. 6 illustrates a bottom view of an anchor housing 600, in accordancewith at least one example of this disclosure. Anchor housing 600 caninclude a secondary bore having a substantially cloverleaf shapeconfigured to promote relatively high angulation of an anchor relativeto the housing. Any of the previously discussed anchor assembly can bemodified include a secondary bore having a substantially cloverleafshape.

The housing 600 can include an anchor bore 616, a distal portion 617,and a secondary bore 622. The secondary bore 622 can include cornernotches 630 a-630 d, and protrusions 632 a-632 d. Also shown in FIG. 6are axis A, and orientation indicators Medial, Lateral, Anterior, andPosterior.

The housing 600 can be similar to other housing discussed above, such ashousing 500, except that secondary bore 622 of housing 600 can have asubstantially cloverleaf shape. That is, the corner notches 630 a-630 dcan have a smaller radius of curvature than corner notches 530 a-530 d,in some examples (though a larger radius can be used in other examples).Further, the corner notches 630 a-630 d can be connected at protrusions632 a-632 d instead of by straight portions. This shape can provide ananchor housing that biases an anchor to extreme angulations, which canbe helpful during a procedure where a desired angulation is known priorto securing the anchor housing to the bone.

FIG. 7 illustrates a bottom view of an anchor housing 700, in accordancewith at least one example of this disclosure. Anchor housing 700 caninclude a secondary bore having a substantially cloverleaf shapeconfigured to promote relatively high angulation of an anchor relativeto the housing. Any of the previously discussed anchor assembly can bemodified include a secondary bore having a substantially cloverleafshape.

The housing 700 can include an anchor bore 716, a distal portion 717,and a secondary bore 722. The secondary bore 722 can include cornernotches 730 a-730 d, and protrusions 732 a-732 d. Also shown in FIG. 7are axis A, and orientation indicators Medial, Lateral, Anterior, andPosterior.

The anchor housing 700 can be similar to anchor housing 600 in thatsecondary opening 722 of the anchor housing 700 can have a substantiallyclover leaf shape. However, the secondary opening 722 of the anchorhousing 700 can be rotated about 90 degrees (in one example) relative tothe secondary opening 622 of the housing 600. This arrangement ofhousing 700 can provide high angulation in the anterior-posteriordirections and can provide higher angulation in the lateral-medialdirections, with respect to the orientation of FIG. 7. This cantranslate to relatively high angulation in the interior-superior(caudal-cranial) directions and to higher angulation in thelateral-medial directions with respect to a patient.

Also, the corner notches 730 a-730 d of the secondary opening of theanchor housing 700 can have a relatively larger radius of curvature thanthe corner notches 630 a-630 d of the housing 600. The larger radius ofcurvature can provide different angulation of the shank relative to thehousing 700, allowing the housing 700 to be used in a larger variety ofangulation applications.

FIG. 8 illustrates a bottom view of an anchor housing 800, in accordancewith at least one example of this disclosure. The anchor housing 800 caninclude a secondary bore having a substantially diamond shape configuredto promote relatively high angulation of an anchor relative to thehousing in anterior, posterior, medial, and lateral directions. Any ofthe previously discussed anchor assembly can be modified include asecondary bore having a substantially diamond shape.

The housing 800 can include an anchor bore 816, a distal portion 817,and a secondary bore 822. The secondary bore 822 can include cornernotches 830 a-830 d, and straight portions 832 a-832 d. Also shown inFIG. 8 are axis A, and orientation indicators Medial, Lateral, Anterior,and Posterior.

The anchor housing 800 can be similar to anchor housing 500 in that thesecondary opening 822 of the anchor housing 800 can have a substantiallygeometric shape of a square with rounded corners. However, the secondaryopening 822 of the anchor housing 800 can be rotated about 90 degrees(in one example) relative to the secondary opening 522 of the housing500. This arrangement of housing 800 can provide high angulation in theanterior-posterior directions and can provide higher angulation in thelateral-medial directions with respect to the orientation of FIG. 8.This can translate to relatively high angulation in theinterior-superior (or caudal-cranial) directions and to higherangulation in the lateral-medial directions, with respect to a patient.

The secondary opening 822 of the anchor housing 800 can also be similarto that of the anchor housing 700, except that the secondary opening 822of the housing 800 includes straight portions 832 a-832 d connecting tocorner notches 830 a-830 d. This can provide relatively smooth movementof the anchor between the corner notches 830 a-830 d.

FIG. 9 illustrates a bottom view of an anchor housing 900, in accordancewith at least one example of this disclosure. Anchor housing 900 caninclude a secondary bore having a substantially ovalar shape configuredto promote relatively high angulation of an anchor relative to thehousing in medial and lateral directions. Any of the previouslydiscussed anchor assembly can be modified include a secondary borehaving a substantially ovalar shape.

The housing 900 can include an anchor bore 916, a distal portion 917,and a secondary bore 922. The secondary bore 922 can include cornernotches 930 a and 930 b, and curved portions 932 a and 932 b. Also shownin FIG. 9 are axis A, and orientation indicators Medial, Lateral,Anterior, and Posterior.

FIG. 9 can be similar to the other housings discussed above, except thatthe secondary opening 922 can have an ovalar shape. More specifically,the secondary opening 922 can include two corner notches 930 a and 930 bconnected by two curved portions 932 a and 932 b. The corner notches 930a and 930 b can provide relatively large angulation of an anchor withrespect to the housing 900 medially-to-laterally and the curved portions932 a and 932 b can provide less extreme angulation of the anchorsuperiorly-to-inferiorly with respect to the housing.

In other examples, oval can be rotated 90 degrees such that thesecondary opening is configured to provide extreme angulation of theanchor with respect to the housing 900 in anterior and posteriordirections with respect to the orientation of FIG. 9, which cantranslate to high angulation in inferior and superior directions whenthe housing 900 is secured to a patient, in some procedures.

NOTES AND EXAMPLES

The following, non-limiting examples, detail certain aspects of thepresent subject matter to solve the challenges and provide the benefitsdiscussed herein, among others.

Example 1 is an anchor assembly couplable to bone, the assemblycomprising: an anchor comprising: a shank securable to bone; and a headcoupled to a proximal portion of the shank; and a housing comprising: aproximal portion including an anchor bore extending distally into thehousing along a longitudinal axis of the housing, the anchor boreconfigured to retain the head of the anchor therein; and a distalportion including a secondary bore configured to engage the anchor tolimit angulation of the anchor relative to the housing, the secondarybore comprising: a first portion configured to limit the angulation ofthe anchor to a first angle relative to the longitudinal axis; and aplurality of second portions each configured to limit the angulation ofthe anchor to a second angle relative to the longitudinal axis that isgreater than the first angle.

In Example 2, the subject matter of Example 1 optionally includeswherein the secondary bore is positioned at a distal end of the distalportion, and wherein the secondary bore is substantially coaxial withthe anchor bore and the longitudinal axis.

In Example 3, the subject matter of any one or more of Examples 1-2optionally include wherein each of the plurality of second portions eachis configured to receive the shank therein and to create a desiredangular trajectory for the shank in reference to the housing.

In Example 4, the subject matter of any one or more of Examples 1-3optionally include wherein the secondary bore has a geometric shapesubstantially of a square with rounded corners from a distalperspective.

In Example 5, the subject matter of any one or more of Examples 1-4optionally include wherein the first portion is defined by a firstchafer extending radially outward from the secondary bore, wherein eachof the plurality of second portions are defined by a plurality of bevelsextending radially outward, and wherein each of the plurality of bevelscurves along a face of each of the plurality of bevels.

In Example 6, the subject matter of any one or more of Examples 1-5optionally include wherein the secondary bore comprises a plurality offirst portions including the first portion, each of the plurality ofsecond portions connected by the plurality of first portions.

In Example 7, the subject matter of Example 6 optionally includeswherein each of the plurality of first portions is substantially planar.

In Example 8, the subject matter of Example 7 optionally includeswherein the shank is threaded and wherein housing includes a helicalgroove configured to receive the threaded shank therethrough.

In Example 9, the subject matter of Example 8 optionally includeswherein the helical groove terminates substantially at connectionbetween one of the plurality of first portions and one of the pluralityof second portions.

In Example 10, the subject matter of any one or more of Examples 6-9optionally include wherein the plurality of first portions and pluralityof second portions are arranged symmetrically about a sagittal plane anda coronal plane of the housing.

In Example 11, the subject matter of any one or more of Examples 2-10optionally include wherein the anchor further comprises a neck includinga neck diameter that is smaller than a diameter of the shank and adiameter of the head, and wherein contact between the neck and thehousing Is configured to limit the angulation of the anchor to thesecond angle relative to the longitudinal axis.

In Example 12, the subject matter of any one or more of Examples 2-11optionally include wherein the housing includes two open sides, eachopen side substantially forming a U shape configured to receive aconnecting member therethrough.

In Example 13, the subject matter of any one or more of Examples 1-12optionally include the assembly further comprising: a lower pistondisposable in the central bore and configured to engage the head; anupper piston disposable in the bore and configured to support aconnecting member; and a biasing element disposable between the lowerpiston and the upper piston to bias the upper piston away from the lowerpiston.

Example 14 is an anchor housing configured to receive an anchortherethrough, the anchor couplable to a bone, the anchor housingcomprising: a proximal portion including an anchor bore extendingdistally into the housing along a longitudinal axis of the housing, theanchor bore configured to receive a shank of an anchor therethrough andconfigured to retain a head of the anchor therein; and a distal portionincluding a secondary opening configured to engage the anchor to limitangulation of the anchor relative to the housing, the secondary borecomprising: a substantially planar face configured to limit theangulation of the anchor to a first angle relative to the longitudinalaxis; and an angled notch configured to limit the angulation of theanchor to a second angle relative to the longitudinal axis that isgreater than the first angle.

In Example 15, the subject matter of Example 14 optionally includeswherein the distal portion further comprises a second angled notchconnected to the first angled notch by the substantially planar face,the second angled notch configured to limit the angulation of the anchorto a third angle relative to the longitudinal axis that is greater thanthe first angle.

In Example 16, the subject matter of Example 15 optionally includeswherein the distal portion further comprises a third angled notch and afourth angled notch, the third angled notch and the fourth angled notchconfigured to limit the angulation of the anchor to a third angle and afourth angle, respectively, relative to the longitudinal axis that aregreater than the first angle.

In Example 17, the subject matter of Example 16 optionally includeswherein the distal portion further comprises a second substantiallyplanar face, a third substantially planar face, and a fourthsubstantially planar face, the first substantially planar face connectedto the first angled notch and the second angled notch, the secondsubstantially planar face connected to the second angled notch and thethird angled notch, the third substantially planar face connected to thethird angled notch and the fourth angled notch, and the fourthsubstantially planar face connected to the first angled notch and thefourth angled notch.

In Example 18, the subject matter of any one or more of Examples 16-17optionally include wherein the first substantially planar face isconnected to the first angled notch defining a first edge and the secondangled notch is connected to the first substantially planar facedefining a second edge, wherein the first substantially planar face isconnected to the first angled notch and the second angled notch to limitengagement of the first edge and the second edge with the anchor.

In Example 19, the subject matter of any one or more of Examples 17-18optionally include wherein a first segment of the first substantiallyplanar face and a third segment of the third substantially planar faceare substantially parallel, and wherein a second segment of the secondsubstantially planar face and a fourth segment of the fourthsubstantially planar face are substantially parallel.

Example 20 is an anchor housing couplable to a bone, the housingcomprising: a proximal portion including an anchor bore extendingdistally into the housing along a longitudinal axis of the housing, theanchor bore configured to receive the shank therethrough and configuredto retain the head of the anchor therein; and a distal portion includinga secondary bore configured to engage the anchor to limit angulation ofthe anchor relative to the housing, the secondary bore comprising: afirst portion configured to limit the angulation of the anchor to afirst angle relative to the longitudinal axis; and a second portionconfigured to limit the angulation of the anchor to a second anglerelative to the longitudinal axis that is greater than the first angle.

In Example 21, the systems, devices, or methods of any one or anycombination of Examples 1-20 can optionally be configured such that allelements or options recited are available to use or select from.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In the event of inconsistent usages between this document and anydocuments so incorporated by reference, the usage in this documentcontrols.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. An anchor assembly couplable to bone, the assembly comprising: ananchor comprising: a shank securable to bone; and a head coupled to aproximal portion of the shank; and a housing comprising: a proximalportion including an anchor bore extending distally into the housingalong a longitudinal axis of the housing, the anchor bore configured toretain the head of the anchor therein; and a distal portion including asecondary bore configured to engage the anchor to limit angulation ofthe anchor relative to the housing, the secondary bore comprising: afirst portion configured to limit the angulation of the anchor to afirst angle relative to the longitudinal axis; and a plurality of secondportions each configured to limit the angulation of the anchor to asecond angle relative to the longitudinal axis that is greater than thefirst angle.
 2. The anchor assembly of claim 1, wherein the secondarybore is positioned at a distal end of the distal portion, and whereinthe secondary bore is substantially coaxial with the anchor bore and thelongitudinal axis.
 3. The anchor assembly of claim 1, wherein each ofthe plurality of second portions each is configured to receive the shanktherein and to create a desired angular trajectory for the shank inreference to the housing.
 4. The anchor assembly of claim 1, wherein thesecondary bore has a geometric shape substantially of a square withrounded corners from a distal perspective.
 5. The anchor assembly ofclaim 1, wherein the first portion is defined by a first chamferextending radially outward from the secondary bore, wherein each of theplurality of second portions are defined by a plurality of bevelsextending radially outward, and wherein each of the plurality of bevelscurves along a face of each of the plurality of bevels.
 6. The anchorassembly of claim 1, wherein the secondary bore comprises a plurality offirst portions including the first portion, each of the plurality ofsecond portions connected by the plurality of first portions.
 7. Theanchor assembly of claim 6, wherein each of the plurality of firstportions is substantially planar.
 8. The anchor assembly of claim 7,wherein the shank is threaded and wherein housing includes a helicalgroove configured to receive the threaded shank therethrough.
 9. Theanchor assembly of claim 8, wherein the helical groove terminatessubstantially at connection between one of the plurality of firstportions and one of the plurality of second portions.
 10. The anchorassembly of claim 6, wherein the plurality of first portions andplurality of second portions are arranged symmetrically about a sagittalplane and a coronal plane of the housing.
 11. The anchor assembly ofclaim 2, wherein the anchor further comprises a neck including a neckdiameter that is smaller than a diameter of the shank and a diameter ofthe head, and wherein contact between the neck and the housing Isconfigured to limit the angulation of the anchor to the second anglerelative to the longitudinal axis.
 12. The anchor assembly of claim 2,wherein the housing includes two open sides, each open sidesubstantially forming a U shape configured to receive a connectingmember therethrough.
 13. The anchor assembly of claim 1, the assemblyfurther comprising: a lower piston disposable in the central bore andconfigured to engage the head; an upper piston disposable in the boreand configured to support a connecting member; and a biasing elementdisposable between the lower piston and the upper piston to bias theupper piston away from the lower piston.
 14. An anchor housingconfigured to receive an anchor therethrough, the anchor couplable to abone, the anchor housing comprising: a proximal portion including ananchor bore extending distally into the housing along a longitudinalaxis of the housing, the anchor bore configured to receive a shank of ananchor therethrough and configured to retain a head of the anchortherein; and a distal portion including a secondary opening configuredto engage the anchor to limit angulation of the anchor relative to thehousing, the secondary bore comprising: a substantially planar faceconfigured to limit the angulation of the anchor to a first anglerelative to the longitudinal axis; and an angled notch configured tolimit the angulation of the anchor to a second angle relative to thelongitudinal axis that is greater than the first angle.
 15. The anchorhousing of claim 14, wherein the distal portion further comprises asecond angled notch connected to the first angled notch by thesubstantially planar face, the second angled notch configured to limitthe angulation of the anchor to a third angle relative to thelongitudinal axis that is greater than the first angle.
 16. The anchorhousing of claim 15, wherein the distal portion further comprises athird angled notch and a fourth angled notch, the third angled notch andthe fourth angled notch configured to limit the angulation of the anchorto a third angle and a fourth angle, respectively, relative to thelongitudinal axis that are greater than the first angle.
 17. The anchorhousing of claim 16, wherein the distal portion further comprises asecond substantially planar face, a third substantially planar face, anda fourth substantially planar face, the first substantially planar faceconnected to the first angled notch and the second angled notch, thesecond substantially planar face connected to the second angled notchand the third angled notch, the third substantially planar faceconnected to the third angled notch and the fourth angled notch, and thefourth substantially planar face connected to the first angled notch andthe fourth angled notch.
 18. The anchor housing of claim 16, wherein thefirst substantially planar face is connected to the first angled notchdefining a first edge and the second angled notch is connected to thefirst substantially planar face defining a second edge, wherein thefirst substantially planar face is connected to the first angled notchand the second angled notch to limit engagement of the first edge andthe second edge with the anchor.
 19. The anchor housing of claim 17,wherein a first segment of the first substantially planar face and athird segment of the third substantially planar face are substantiallyparallel, and wherein a second segment of the second substantiallyplanar face and a fourth segment of the fourth substantially planar faceare substantially parallel.
 20. An anchor housing couplable to a bone,the housing comprising: a proximal portion including an anchor boreextending distally into the housing along a longitudinal axis of thehousing, the anchor bore configured to receive the shank therethroughand configured to retain the head of the anchor therein; and a distalportion including a secondary bore configured to engage the anchor tolimit angulation of the anchor relative to the housing, the secondarybore comprising: a first portion configured to limit the angulation ofthe anchor to a first angle relative to the longitudinal axis; and asecond portion configured to limit the angulation of the anchor to asecond angle relative to the longitudinal axis that is greater than thefirst angle.